Grant-Free NOMA Through Optimal Partitioning and Cluster Assignment in STAR-RIS Networks
Naim Shaikh M.H. Celik A. Eltawil A.M. Nauryzbayev G.
2024Institute of Electrical and Electronics Engineers Inc.
IEEE Transactions on Wireless Communications
2024#23Issue 810166 - 10181 pp.
The integration of reconfigurable intelligent surfaces (RISs) and grant-free non-orthogonal multiple access (GF-NOMA) has emerged as a promising solution for enhancing spectral efficiency and massive connectivity in future wireless networks. This paper proposes a GF-NOMA communication network enabled by simultaneously transmitting and reflecting RISs (STAR-RIS). In the proposed GF-NOMA, all user equipments (UEs) have instantaneous access to resource blocks (RBs) without the need for grant acquisition and power control as in the traditional grant-based NOMA schemes. Specifically, we have considered two regimes of interest: 1) the max-min fair (MMF) regime and 2) the max-sum throughput (MST) regime. To achieve the required power disparity, a two-level power control mechanism is proposed; initially, the UEs are clustered according to their channel gains. Additionally, we introduce a multi-level GF-NOMA (MGF-NOMA) scheme that adjusts the transmit power levels for each UE in the cluster. The second level of power disparity is achieved through the assignment of STAR-RISs to the clusters and optimal partitioning of STAR-RIS to support each of the cluster members. Furthermore, we have also derived the closed-form equations for the optimal partitioning of STAR-RIS within the clusters for both regimes of interest. Simulation results demonstrate that the proposed STAR-RIS-aided MGF-NOMA yields a gain of 60% and 20% in the MST regime with active and passive RIS realization, respectively. Furthermore, the active and passive RIS-based MGF-NOMA achieve nearly the equivalent fairness that can be obtained through optimal power control in the MMF regime. The finding emphasizes the potential of integrating STAR-RIS with GF-NOMA as a robust and promising solution for future wireless communication systems.
fairness , grant-free NOMA , max-min optimization , max-sum rate , non-orthogonal multiple access (NOMA) , Reconfigurable intelligent surface (RIS) , simultaneously transmitting and reflecting RIS (STAR-RIS) , spectral efficiency
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Nazarbayev University, School of Engineering and Digital Sciences, Astana, 010000, Kazakhstan
King Abdullah University of Science and Technology, Computer, Electrical and Mathematical Sciences and Engineering Division, Thuwal, 23955, Saudi Arabia
Nazarbayev University
King Abdullah University of Science and Technology
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026